What defines an atmospheric tank?

An atmospheric tank is characterized by its design to operate at atmospheric pressure, which is defined as pressures up to 1.0 psi gauge. This means the internal pressure of the tank does not exceed the atmospheric pressure outside it. Atmospheric tanks are typically used for the storage of fluids such as liquids and gases that do not need to be stored at elevated pressures.

Understanding this definition is crucial for ensuring the proper management and safety protocols are followed when handling non-flammable medical gases, as the pressure conditions directly affect the tank's design and operational safety guidelines. The other options describe tanks with different operational pressures or functions, which do not fit the criteria for an atmospheric tank and are therefore not applicable.